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Switch M17 Rx sample rate to 5SPS 

Due to the RRC computation sometimes violating the timing constraints,
we switched the M17 demodulator to 5 samples per symbol (24KHz), thus
dividing the processing time by four ar the number of samples halves as
well as the number of taps of the RRC.
Minor adaptation on the code followed.

TG-81
This commit is contained in:
Niccolò Izzo 2022-04-26 08:41:48 +02:00 committed by Silvano Seva
parent e68b05d859
commit b1f2cb109f
1 changed files with 13 additions and 13 deletions
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26
openrtx/src/protocols/M17/M17Demodulator.cpp
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@ -254,9 +254,9 @@ int8_t M17Demodulator::quantize(int32_t offset)
sample = basebandBridge[M17_BRIDGE_SIZE + offset];
else // Otherwise use regular data buffer
sample = baseband.data[offset];
if (sample > static_cast< int16_t >(qnt_pos_avg / 1.7))
if (sample > static_cast< int16_t >(qnt_pos_avg / 2.1))
return +3;
else if (sample < static_cast< int16_t >(qnt_neg_avg / 1.7))
else if (sample < static_cast< int16_t >(qnt_neg_avg / 2.1))
return -3;
else if (sample > 0)
return +1;
@ -343,32 +343,32 @@ bool M17Demodulator::update()
int8_t symbol = quantize(symbol_index);
#ifdef PLATFORM_LINUX
for (int i = 0; i < 4; i++)
for (int i = 0; i < 2; i++)
{
if ((symbol_index - 4 + i) >= 0)
if ((symbol_index - 2 + i) >= 0)
fprintf(csv_log, "%" PRId16 ",%d,%f,%d,%" PRId16 ",%f,%f,%d,%d\n",
0,0,0.0,symbol_index - 4 + i,
baseband.data[symbol_index - 4 + i],
qnt_pos_avg / 1.7,
qnt_neg_avg / 1.7,
0,0,0.0,symbol_index - 2 + i,
baseband.data[symbol_index - 2 + i],
qnt_pos_avg / 2.1,
qnt_neg_avg / 2.1,
0,
frame_index);
}
fprintf(csv_log, "%" PRId16 ",%d,%f,%d,%" PRId16 ",%f,%f,%d,%d\n",
0,0,0.0,symbol_index,
baseband.data[symbol_index],
qnt_pos_avg / 1.7,
qnt_neg_avg / 1.7,
qnt_pos_avg / 2.1,
qnt_neg_avg / 2.1,
symbol * 666,
frame_index);
for (int i = 0; i < 5; i++)
for (int i = 0; i < 2; i++)
{
if ((symbol_index + i + 1) < static_cast<int32_t> (baseband.len))
fprintf(csv_log, "%" PRId16 ",%d,%f,%d,%" PRId16 ",%f,%f,%d,%d\n",
0,0,0.0,symbol_index + i + 1,
baseband.data[symbol_index + i + 1],
qnt_pos_avg / 1.7,
qnt_neg_avg / 1.7,
qnt_pos_avg / 2.1,
qnt_neg_avg / 2.1,
0,
frame_index);
}